     (/ n div)))
 
 (defn ^BigDecimal bigdecimal
-  "Convert x to a java.math.BigDecimal, representing ratios as doubles"
-  [x]
-  (if (ratio? x)
-    (bigdec (double x))
-    (bigdec x)))
+  "Convert v to a java.math.BigDecimal, representing ratios as doubles"
+  [v]
+  (if (ratio? v)
+    (bigdec (double v))
+    (bigdec v)))
 
 (defn ^BigDecimal round-bigdecimal
   "Round BigDecimal `v` to specified number of significant digits"

  (:import (java.math BigDecimal MathContext RoundingMode)))

(defn nonzero?
  "Is x non-nil and non-zero?"
  [x]
  (and x (not= 0 x)))

(defn divide-some
  "Zero-safe division (returns value or nil)"

  "Return the arithmetic mean of vs, or nil if empty"
  [vs]
  (when (seq vs)
    (/ (reduce + vs) (count vs))))

(defn median
  "Return the median value of vs, or nil if empty"
